A monopulse antenna system is commonly used to implement radar tracking. As its name implies, for a radar application a monopulse antenna system employs a single pulse to identify the presence of an object in the field of view. This is possible due to the use of multiple antenna elements which can detect angle information from the received signal. A monopulse antenna system can also be used to track intentional radiators.
FIG. 1 illustrates an example block diagram of a typical dual-axis monopulse antenna system. As shown, a dual-axis monopulse antenna system may include four antenna elements (A, B, C, and D) each of which receive the same signal. If an object is in the field of view of the monopulse antenna system, each antenna element will receive the reflected signal. These received signals (which are referred to as A, B, C, and D respectively) are then fed to a comparator network.
Due primarily to the slight differences in the positions/orientations of the antenna elements, the characteristics of the received signals will vary. The comparator network can detect these variations to allow the relative location of the object with respect to the boresight axis to be determined. In particular, the comparator network can generate three tracking channels: (1) a sum (Σ) of the four received signals; (2) an azimuth difference (Δaz); and (3) an elevation difference (Δel). As one of skill in the art would understand how these tracking channels can be employed to identify and track the position of an object, no further description will be provided.
In typical monopulse antenna systems, the system is steered so that the object to be tracked will remain in the field of view. To facilitate steering, the monopulse antenna system is typically mounted to a pedestal. However, such configurations may be undesirable in many situations such as on aircraft where a pedestal-mounted system would require undesirable aircraft fuselage changes to accommodate the system and to minimize drag.